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The Quaternary was the main evaporite deposition period in the Qaidam Basin (QB), but the correlation between the evaporite deposition period and the glacial period is still unclear. In this study, the research objects are primarily evaporite‐bearing strata in a 461.58 m‐long drill core in the QB. X‐ray powder diffraction (XRD) and scanning electron microscopy (SEM) were applied to study the evaporite minerals, U‐Th dating being applied to construct the 230Th geochronological framework. Evaporite deposition from Marine Isotope Stage (MIS) 15 to MIS 4 in the borehole was reconstructed via mineralogical and geochronological data. The evaporite minerals are mainly halite (NaCl), mirabilite (Na2SO4·10H2O), thenardite (Na2SO4) and gypsum (CaSO4·2H2O). A total of 9 effective 230Th data points, ranging from 492.5 ± 43.0 ka to 62.0 ± 11.9 ka, were obtained. The depositional age of the earliest halite layer in the borehole is 592.5–563.0 ka. There were mirabilite deposits in the QB during the cold glacial environment of MIS 6. During MIS 4, the study area desiccated, with mirabilite and halite being deposited. This study suggests that mirabilite is an indicator mineral for the glacial environment in the QB, while halite deposition does not correspond well to glaciation. [ABSTRACT FROM AUTHOR]

The ammonium sulfate‐soda method is a procedure that produces soda ash and the by‐product ammonium sulfate, using mirabilite as the raw material. Here, a process for producing soda ash by the ammonium sulfate‐soda method is proposed. Based on the reaction mechanisms occurring in the Na2SO4‐NH3‐CO2‐H2O system and the kinetic‐thermodynamic data of the CO2 absorption process using aqueous NH3, the soda ash production process is modeled and simulated using Aspen Plus. The effects of various process parameters (the concentration of the raw mirabilite solution, the amounts of NH3 and CO2 flowing into the process, and the recycle ratio of CO2 exhausted from the NaHCO3 calciner, etc.) on the process performance are investigated. [ABSTRACT FROM AUTHOR]

The Raman spectra of the Na2SO4‐K2SO4‐H2O system are not well‐defined in the literature. Specifically, the proper identification of sodium and potassium sulphate (aphthitalite or glaserite, K3Na(SO4)2) and anhydrous sodium sulphate (thenardite, Na2SO4) is particularly problematic because their vibrational profiles present the same main Raman peak at 993 cm−1 and very similar low frequency bands. As proved in bibliography, the similarity of their spectra can often lead to uncertain or erroneous identifications. Considering that aphthitalite and thenardite can be found as degradation products on built heritage materials and the degree of danger associated to them is not the same, being the second one the most harmful, the resolution of this problem has a critical importance. For this reason, in the present work, the Raman spectra of aphthitalite and thenardite are deeply studied to identify the vibrational fingerprints enabling their correct identification. The results here summarized and provided by two different Raman instruments highlight that the spectrum of aphthitalite displays characteristic bands at 1,084 and 1,202 cm−1. In contrast, the bands at 1,100, 1,129, and 1,152 cm−1 seem to be characteristic of thenardite. Furthermore, when those secondary bands are not observed or mixtures of both compounds are present, the ratio between their most intense bands at 452 and 993 cm−1 is the key for their correct characterization. On the whole, this study fills the gaps observed in literature and gives the solution for the correct identification of aphthitalite and thenardite even when secondary bands are not observed. This study fills the gaps observed in literature in the Raman spectra of the Na2SO4‐K2SO4 system by 532 and 785‐nm excitation lasers, which has a relevant importance in built heritage studies, giving the solution for the correct identification of aphthitalite and thenardite even when secondary bands are not observed. [ABSTRACT FROM AUTHOR]

Neutron powder diffraction data have been collected from Na2SO4·10D2O (the deuterated analogue of mirabilite), a highly hydrated sulfate salt that is thought to be a candidate rock-forming mineral in some icy satellites of the outer solar system. These measurements, made using the OSIRIS instrument on the ISIS neutron spallation source, covered the range 0.1 < P < 545 MPa and 150 < T < 270 K. The refined unit-cell volumes as a function of pressure and temperature are parameterized in the form of a Birch-Murnaghan third-order equation of state, and the anisotropic linear incompressibilities are represented in terms of the elastic strain tensor. At 270 K, the bulk modulus K0,270 = 19.6 (1) GPa, its first pressure derivative ∂ K/∂ P = 5.8 (5) and its temperature dependence ∂ K/∂ T = −0.0175 (6) GPa K−1. The stiffest direction at 270 K, with a linear bulk modulus of ∼82 GPa, is coincident with the twofold axis of this monoclinic crystal. Of the remaining two principal directions, the most compressible ( K≃ 44 GPa) is roughly aligned with the c axis, and the intermediate value ( K≃ 59 GPa) is therefore approximately collinear with a*. With the aid of additional published data, a number of other important thermodynamic quantities have been derived, including the Grüneisen and Anderson-Grüneisen parameters, and the volume and enthalpy of melting along the high-pressure melting curve. Additional data obtained during this work, concerning the elastic properties of deuterated ice IV, are also presented. [ABSTRACT FROM AUTHOR]

Dahuang‐mudan decoction (DMD) has been widely used for disease treatment in China for 1700 years. The formula consists of Rhubarb, moutan bark, Prunus persica, wax gourd kernel and mirabilite, which have been well studied by multidisciplinary approaches. However, the role of the mineral mirabilite in DMD is unclear. The objective of this study was to investigate the effects of mirabilite on the absorption and pharmacokinetics of the ingredients in DMD. The constituents were identified in DMD extract and the plasma of mirabilite–DMD (MDMD, 50 g kg−1) treated rats and nonmirabilite–DMD (NMDMD, 50 g kg−1) treated rats. The plasma was also used to investigate the effects of mirabilite on the pharmacokinetics of active ingredients in DMD using a new validated UPLC–MS/MS method. The results showed that 63 compounds were identified in the extract of DMD, 27 and 22 of which were found in the plasmas of MDMD‐ and NMDMD‐treated rats, respectively. Furthermore, the results of a pharmacokinetic study suggested that mirabilite influenced the absorption of the five constituents by decreasing the absorption of emodin and rhein while increasing the absorption of aloe‐emodin, paeoniflorin and amygdalin; the pharmacokinetic parameters, including the Tmax, Cmax, AUC0–t, MRT0–t, CLz and t1/2 of five constituents, significantly changed in MDMD‐treated rats compared with the NMDMD. The method validation for selectivity, precision, accuracy, matrix effect, recovery and stability met the acceptance criteria. These findings uncover the roles of mirabilite in DMD and demonstrate the application of scientific principles to the study of DMD in human health care. [ABSTRACT FROM AUTHOR]